The present invention relates to hot gas path components in gas turbines made of nickel and cobalt base superalloy castings.
Castings employed in gas turbines are either equiaxed, directionally solidified or single crystal in nature. Many of these cast components require additional fabrication steps to achieve the final product. One of the operations during the OEM (Original Equipment Manufacture) fabrication, or during service repair, is fusion welding.
It is known that superalloys generally have poor weldability. They suffer from liquation and strain age cracking in the heat affected zone (HAZ) of the weldment. In particular, these cracks generally occur at the grain boundaries (in equiaxed and DS grain alloys).
A need exists to minimize or prevent cracking in the heat affected zone (HAZ) of the weldment due to the stringent defect size requirements depending on the stress and temperature experienced by the location during operation. The present invention seeks to satisfy that need.